Hach Paddle Testers allow fast, easy screening of water samples, solid surfaces, and nonviscous liquids where unsanitary conditions may exist. The paddle is a double-sided slide attached to the vial cap. Each side of the slide is used to perform a separate test. The slide has a molded-in grid for easy colony counting without opening the optically clear, leakproof vial.Paddle Tester, Total Aerobic Bacteria/Total Coliforms (Tryptic Soy Agar/Violet Red Bile Agar), pk/10.